Flow Field in a Rectangular Basin with a Line Inlet and a Circular Outlet

Abstract

An experimental study was conducted to investigate the flow field in a rectangular basin with a line inlet and a circular outlet. The basin has a length about four times of the water depth and the outlet level was varied in the study. The flow field in the basin can be characterized into three zones: the wall jet zone with an induced recirculation eddy, the outlet zone in the vicinity of the outlet, and the transition zone in between the two zones. The spreading of the wall jet was found to significantly exceed that of a classical wall jet. In the transition zone, the wall jet separated from the basin bed due to the adverse pressure gradient created by the jet impingement on the outlet wall. Upstream of the outlet, a special three-dimensional balloon-like flow pattern was observed. Within a distance of three times of the outlet diameter, potential flow theory predicts well the measured velocity.